In our earlier International Patent Application No WO 02/15698, we described the preparation of articles having a contact biocidal property. A polymer solution which contains atomic/metallic silver in suspension or complexed with the polymer is applied to a substrate by impregnation or surface deposition and the article is dried. Alternatively the polymer solution contains a silver compound in solution, in suspension or complexed with the polymer instead of the atomic/metallic silver, and the silver compound is reduced to atomic/metallic silver after the application to the substrate. A second alternative is to convert the polymer solution to a fibre, film, powder or foam, effectively forming the article from the polymer solution instead of coating an existing article.
A disadvantage of the invention described in WO 02/15698 is the large liquor quantities resulting from the low solubility of the preferred polymer, chitosan. This can result in the use of an uneconomic quantity of silver. Also, transportation of solutions is expensive, and this may economically limit the applications of the prior invention.